linux-kernel - [PATCH] f2fs: fix to do sanity check on segment type in build_sit

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Date:   Wed, 27 Jul 2022 22:51:05 +0800
From:   Chao Yu <chao@...nel.org>
To:     jaegeuk@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chao Yu <chao.yu@...o.com>,
        Wenqing Liu <wenqingliu0120@...il.com>
Subject: [PATCH] f2fs: fix to do sanity check on segment type in build_sit_entries()

From: Chao Yu <chao.yu@...o.com>

As Wenqing Liu <wenqingliu0120@...il.com> reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=216285

RIP: 0010:memcpy_erms+0x6/0x10
 f2fs_update_meta_page+0x84/0x570 [f2fs]
 change_curseg.constprop.0+0x159/0xbd0 [f2fs]
 f2fs_do_replace_block+0x5c7/0x18a0 [f2fs]
 f2fs_replace_block+0xeb/0x180 [f2fs]
 recover_data+0x1abd/0x6f50 [f2fs]
 f2fs_recover_fsync_data+0x12ce/0x3250 [f2fs]
 f2fs_fill_super+0x4459/0x6190 [f2fs]
 mount_bdev+0x2cf/0x3b0
 legacy_get_tree+0xed/0x1d0
 vfs_get_tree+0x81/0x2b0
 path_mount+0x47e/0x19d0
 do_mount+0xce/0xf0
 __x64_sys_mount+0x12c/0x1a0
 do_syscall_64+0x38/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The root cause is segment type is invalid, so in f2fs_do_replace_block(),
f2fs accesses f2fs_sm_info::curseg_array with out-of-range segment type,
result in accessing invalid curseg->sum_blk during memcpy in
f2fs_update_meta_page(). Fix this by adding sanity check on segment type
in build_sit_entries().

Reported-by: Wenqing Liu <wenqingliu0120@...il.com>
Signed-off-by: Chao Yu <chao.yu@...o.com>
---
 fs/f2fs/segment.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 51da73b27a45..7b1d2c29aba6 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -4375,6 +4375,12 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
 				return err;
 			seg_info_from_raw_sit(se, &sit);
 
+			if (se->type >= NR_PERSISTENT_LOG) {
+				f2fs_err(sbi, "Invalid segment type: %u, segno: %u",
+							se->type, start);
+				return -EFSCORRUPTED;
+			}
+
 			sit_valid_blocks[SE_PAGETYPE(se)] += se->valid_blocks;
 
 			if (f2fs_block_unit_discard(sbi)) {
@@ -4423,6 +4429,13 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
 			break;
 		seg_info_from_raw_sit(se, &sit);
 
+		if (se->type >= NR_PERSISTENT_LOG) {
+			f2fs_err(sbi, "Invalid segment type: %u, segno: %u",
+							se->type, start);
+			err = -EFSCORRUPTED;
+			break;
+		}
+
 		sit_valid_blocks[SE_PAGETYPE(se)] += se->valid_blocks;
 
 		if (f2fs_block_unit_discard(sbi)) {
-- 
2.36.1